The present invention relates to a hydraulic submersible rotary pump and drive assembly which can be deployed and recovered through production tubing or casing. The present assembly can be used in conventional oil and gas well bores, but is particularly advantageous in slant or horizontal oil and gas well bores for artificial fluid lift or water injection.
Present submersible rotary pump drives for oil well artificial lift systems rely on deploying the pumps and drive systems on the production tubing as opposed to conventional reciprocating pumping systems which are deployed through the production tubing on a sucker rod string. Subsurface electric drives have been developed for certain rotary artificial lift systems but are not suitable for deployment through tubing because of there size and the fragile nature of the electric supply cable which would have to be used for deployment and recovery. Hydraulic submersible rotary pump drives which are just being proven for oil field artificial lift, particularly in slant and horizontal applications, are presently deployed only on production tubing for insertion into a well.
What is therefore desired is a novel hydraulic submersible rotary pump and drive assembly which can be deployed and recovered through production tubing using hydraulic metal tubing lines. In particular, the drive assembly should incorporate a ported torque neutralizing connector sub to attach a suitable hydraulic drive motor to a selected submersible rotary production pump. The pump drive should also incorporate the use of a conventional pump seating nipple in the production tubing and seating cup assembly on the drive to seal the pump discharge from the pump suction within the tubing as is common with conventional insert pumps. In an alternate version, the assembly should be capable of being used with a pack-off assembly (rather than the pump seating nipple) to seal against a production casing or open hole when it is desirable not to use production tubing.
In one aspect the invention provides a means for oil field operators to eliminate mechanical drive shafts running from surface to a bottom hole rotary pump, which are the most problematic area of conventional pumping systems. Unlike conventional systems and other submersible drives, the present invention allows rotary pumps to be changed without pulling out the production tubing. Considerable cost savings should be realized for oil field operators by not having to pull production tubing to service a submersibly driven or conventional rotary pump.
In another aspect of this invention, it provides a ported, torque neutralizing connector sub with a motor mount end and a pump mount end having:
left-hand threaded, or locking, connections to counteract the right-hand turn of the drive shaft;
a hollow interior which allows for a drive shaft to be connected from a hydraulic motor to the rotor of a rotary pump;
one or more ports in the connector sub to allow produced fluid to exit the connector sub into the production tubing or casing for passage therethrough; and,
a means to seal the pump discharge from the pump suction within the well bore tubings.